With the development of science and technology, electronic devices, such as smart phones, laptops, etc., have been widely used in daily life. A user can watch various videos online through a browser installed in an electronic device, and even download these video.
During the video download process, a download progress bar may be dragged into a rear position by a user. In this case, it is possible to continue downloading the video data starting from the current position since the skipped areas produced by the user's drag operation need to be filled with invalid data (hereinafter briefly referred to as “invalid data area”). When the skipped areas produced by dragging video files are large the space of invalid data areas is very large, affecting the speed for downloading video data.